Non-volatile resorcinolic resins and methods of making and using the same

ABSTRACT

Methods for preparing low free resorcinol resins are disclosed. These methods generally comprise reacting a resin with an aromatic olefinic compound; suitable resins include one or more resins selected from the group consisting of a dihydric phenol, a polyhydric phenol, a dihydric phenolic novolak resin and a polyhydric phenolic novolak resin; the addition product of at least one of these resins and at least one compound selected from the group consisting of a monooxirane compound and a polyoxirane compound; and a phenol or alkyl or aralkyl substituted mono- or dihydric phenol modified form of these resins. The resins produced by this method are also disclosed, as are rubber compositions utilizing the resin produced by this method.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates Lo improved resorcinolic resins having a low freeresorcinol content, and methods of making and using the same. Theseresins are particularly useful as bonding and stiffening agents in theproduction of rubber compositions, imparting improved physical andmechanical properties such as low volatility, reduced fuming in rubbercompounding, and improved adhesion properties of vulcanized rubber andrubber composites.

2. Background Information

The performance of rubber composites in articles such as tires, beltsand hose products depends on numerous factors including the quality ofadhesion between the rubber and reinforcing materials, and themechanical properties of the cured rubber matrix in contact with thereinforcing materials.

The conventional method of optimizing the adhesion of the rubber to thereinforcement entails compounding into the rubber before vulcanization atwo-part adhesive system that includes a methylene donor and a methyleneacceptor. The methylene donor generates methylene or methylol groupscapable of reacting or crosslinking with the methylene acceptor, whichinteracts with the rubber and reinforcing material with a resultantincrease in adhesion of the rubber to the reinforcing material. Becausethe methylene donor and the methylene acceptor are compounded into therubber, they can have a significant effect on the properties of thefinal rubber product.

Dihydric phenols, polyhydric phenols and phenolic novolak resins havelong been used in the rubber industry as methylene acceptors. Forexample, resorcinol is a widely used dihydric phenol methylene acceptorfor bonding rubber to the reinforcing materials. Resorcinolic methyleneacceptors can present processing problems, however, by generatingvolatiles such as free resorcinol at Banbury temperatures.

The most commonly used methylene donors include, for example,hexamethylenetetramine and various methylol or methoxymethyl melamines.Other methylene donors are described in U.S. Pat. No. 3,751,331.

The in situ resin formed by the reaction of the resorcinolic methyleneacceptor and the methylene donor promotes adhesion between the rubberand reinforcing materials which include, for example, steel, glass andorganic filaments, fibers, cords and fabrics. In addition, theresorcinolic resin also provides rubber vulcanizates with improvedhardness and dynamic stiffness properties. These compounding additivesalso act as thermosetting plasticizers, providing easier processibility,and excellent extrusions for the rubber compounds. The disadvantage,however, of these resorcinolic compounding additives is that they cangenerate an undesirable amount of fuming in Banbury mixing andcalendaring operations.

U.S. Pat. No. 4,889,891 discloses alkyl substituted resorcinolic novolakresins as suitable methylene acceptors for vulcanizable rubbercompositions.

U.S. Pat. No. 4,892,908 discloses the use of keto derivatives ofresorcinol, such as benzoyl resorcinol, as methylene acceptors invulcanizable rubber compositions.

U.S. Pat. No. 4,605,696 discloses use of monoesters of resorcinol,including resorcinol monobenzoate and resorcinol monorosinate, in rubbercompositions.

U.S. Pat. No. 5,021,522 discloses aralkyl substituted resorcinolicnovolak resins including a styrene substituted resorcinol formaldehyderesin.

U.S. Pat. No. 5,030,692 discloses alkylphenol modified resorcinolicnovolak resins.

U.S. Pat. No. 4,731,430 discloses phenol resins modified with compoundspossessing amide and/or imide groups that are useful as crosslinkingagents and in the preparation of adhesives and rubber assistants.

U.S. Pat. No. 4,990,364 describes a process for producing porousphenolic resin fibers including the step of thermally decomposing agraft polymer containing a vinyl group.

U.S. Pat. No. 5,244,725 discloses a vulcanizable rubber composition thatincludes a rubber component, a methylene donor and a methylene acceptor.

U.S. Pat. No. 4,476,262 discloses a water dilutable resinous productprepared by reacting together a resin, an aldehyde and a sulfurous ororganic acid.

There remains, however, a very real and substantial need for furtherimproved bonding additive resins that may be used as methylene acceptorsand that, in combination with suitable methylene donors, have enhancedcuring properties, mechanical properties, and improved bonding andstiffening properties in vulcanizable rubber compositions. In addition,there remains a very real and substantial need for non-volatileresorcinol resins.

SUMMARY OF THE INVENTION

The present invention has met the above-described needs. The presentinvention provides a method for reducing the free monomer content in aresin comprising reacting the resin with an aromatic olefinic compound.Suitable resins include, for example, one or more resins selected fromthe group consisting of a dihydric phenol, a polyhydric phenol, adihydric phenolic resin and a polyhydric phenolic resin; the additionproduct of at least one of these resins and at least one compoundselected from the group consisting of a monooxirane compound and apolyoxirane compound; and the phenol or alkyl or aralkyl substitutedmono- or dihydric phenol modified forms of these resins. The presentinvention also provides the low free resorcinol resins produced by thismethod.

Another embodiment of this invention provides a rubber compositioncomprising: (a) a rubber component; (b) a methylene donor; and (c) amethylene acceptor; the methylene acceptor is prepared by reacting anaromatic olefinic compound with a resin such as those described above.Reinforced rubber articles further comprising (d) a reinforcing materialare also provided by the present invention.

It is an object of the present invention to provide a method forreducing the free monomer content in a resin.

It is an object of the present invention to provide a method forproducing a resorcinolic resin with a low free resorcinol content.

It is another object of the present invention to provide a resin havinga low free monomer content.

It is a further object of the present invention to provide aresorcinolic resin with a low free resorcinol content.

It is another object of the present invention to provide a resorcinolicresin having a low free resorcinol content for use in rubber compoundingapplications.

It is a further object of the present invention to provide a resin witha free resorcinol content near zero.

It is another object of the present invention to provide a method forproducing a resorcinolic resin with a yield near 100%.

It is a further object of the present invention to provide avulcanizable rubber composition having improved physical and mechanicalproperties.

It is another object of the present invention to provide a vulcanizablerubber composition having improved adhesion between the rubber andreinforcing material, while at the same time having improved mechanicalproperties for the cured rubber matrix in contact with the reinforcingmaterial.

These and other objects of the invention will be more fully understoodfrom the following description of the invention and the claims appendedhereto.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is directed to a method for reducing the freemonomer content in a resin comprising reacting an effective amount of anaromatic olefinic compound with the resin. Suitable resins for use inthe present invention include, but are not limited to, one or moreresins selected from the group consisting of a dihydric phenol, apolyhydric phenol, a dihydric phenolic resin and a polyhydric phenolicresin; the addition product of at least one compound selected from thegroup consisting of a dihydric phenol, a polyhydric phenol, a dihydricphenolic resin and a polyhydric phenolic resin, and at least onecompound selected from the group consisting of a monooxirane compoundand a polyoxirane compound; and a phenol or alkyl or aralkyl substitutedmono- or dihydric phenol modified resin selected from the groupconsisting of at least one dihydric phenol, polyhydric phenol, dihydricphenolic resin and polyhydric phenolic resin.

As will be appreciated by one skilled in the art, the reaction betweenthe resin and the aromatic olefinic compound is an additionpolymerization. The product resulting from the method of the presentinvention is a resin having a low free monomer content. Typically, themonomer will be resorcinol, although the content of other free monomersexisting in the resin will also be reduced. Other free monomers include,for example, phenols, alkylphenols and alkylresorcinols.

As used herein, "low free resorcinol" refers to resins that have a lowcontent of unreacted resorcinol. Preferably, the free resorcinol contentof these resins is less than 10% unreacted resorcinol, more preferablyless than 5% unreacted resorcinol, and most preferably less than 1%unreacted resorcinol.

The di- or polyhydric phenols of the invention include, but are notlimited to, resorcinol, catechol, dihydroxybiphenol, trihydroxybiphenol,hydroquinone, alkylidenebisphernols or thio-bisphenols. The alkylidenegroup of the alkylidenebisphenols can have from about 1 to 12 carbonatoms. The alkylidenebisphenols include, but are not limited to,4,4'-methylenediphenol (bisphenol F), and 4,4'-isopropylidenediphenol(bisphenol A). The di- or polyhydric phenolic resins of the presentinvention include di- or polyhydric phenol including, but not limitedto, resorcinol, catechol, dihydroxybiphenol, trihydroxybiphenol,hydroquinone or aldehyde resins thereof.

Also within the scope of the invention are di- or polyhydric phenolsthat are substituted by at least one of the groups including an alkylgroup having from about 1 to 12 carbon atoms, an aralkyl group havingfrom about 6 to 12 carbon atoms, an alkanoyl group having from about 2to 18 carbon atoms, an aroyl group having from about 7 to 11 carbonatoms or a halogen selected from the group consisting of chlorine andbromine.

"Oxirane" refers to the epoxide or alkylene oxide group having a generalstructure of formula (1) ##STR1## wherein X represents the point ofattachment to the remainder of the molecule. It is well known by thoseskilled in the art that the epoxide function generally appears in thegeneral structural form of formula (2) ##STR2## which is known as theglycidyl group and is attached to the remainder of a compound by, forexample, an oxygen (a glycidyl ether), a nitrogen (a glycidyl amine oramide), or a carboxyl group (a glycidyl ester).

The monooxirane compounds of this invention include, but are not limitedto, saturated or unsaturated alkylene oxides having from about 2 to 18carbon atoms, a glycidyl ether compound, a glycidyl ester compound, ormixtures thereof. The saturated alkylene oxide compounds include, forexample, ethylene oxide, α-olefin oxides having from about 4 to 18carbon atoms, propylene oxide, styrene oxide, cyclohexene oxide,4-vinylcyclohexenemonoxide, glycidol or mixtures thereof. Unsaturatedalkylene oxides including at least 1 carbon-to-carbon unsaturated bondare also within the scope of the invention.

The polyoxirane compounds as used in the present invention include, butare not limited to, 4-vinylcyclohexenedioxide, epoxidized glycerides ofunsaturated fatty acids, epoxidized nitrogen-containing material, epoxytallate, polyglycidyl ethers, polyglycidyl esters, or mixtures thereof.The polyglycidyl ethers include, for example, diglycidyl ether ofbisphenol A, diglycidyl ether of bisphenol F, trimethylol propanetriglycidyl ether, a polyglycidyl ether of castor oil, abis(3,4-epoxycyclohexyl) adipate, a dibromo-neopentyl diglycidyl ether,or a glycidyl ether of a novolak epoxy resin. The glycidyl ether of thenovolak epoxy resin includes, for example, polyglycidyl ethers of thedi- or polyhydric phenolic resins as described above. The epoxidizednitrogen-containing material of the polyoxirane compound includes, forexample, triglycidyl isocyanurate or triglycidyl para-aminophenol.

An effective amount of the aromatic olefinic compound should be used. Asused herein, the term "effective amount" refers to that amount of anaromatic olefinic compound needed to "tie up" the free monomer in theresin. This amount will vary depending on the resin used and the initialfree monomer content, and can be readily determined by one skilled inthe art. The aromatic olefinic compounds as used in the presentinvention include any aromatic olefinic compounds of the general formula(3). ##STR3## wherein R is selected from the group consisting of H, CH₃and halogen, and R₁ is independently selected from the group consistingof H, OH, an alkyl group having from 1 to 6 carbons, a halogen and--CH=CH₂. Preferably, the aromatic olefinic compound is an aromaticvinyl compound including alpha-methylstyrene, p-methylstyrene,alpha-chlorostyrene and divinylbenzene. Most preferred is styrene. Vinylnaphthalenes are also aromatic olefinic compounds within the scope ofthe invention.

If the resin used is the addition product of at least one compoundselected from the group consisting of a dihydric phenol, a polyhydricphenol, a dihydric phenolic resin and a polyhydric phenolic resin and atleast one compound selected from the group consisting of a monooxiranecompound, and a polyoxirane compound, this reaction is preferablyperformed first. This reaction is facilitated by the use of a catalyst,including but not limited to a catalyst selected from the groupconsisting of trialkylphosphine, triarylphosphines, trialkylamines,dialkylaminomethylated phenol, 4-dimethylaminopyridine or other organicor inorganic bases, or a quaternary ammonium compound. Suitablequaternary ammonium compounds include, but are not limited to,tetraalkylammonium halides or sulfates such as tetrabutylanimoniumhalide or sulfate, and benzyltrimethylammonium halide or hydroxide. Aswill be appreciated by one skilled in the art, these catalysts aremildly basic. The preferred catalyst for use in the reaction of step (a)is triphenylphosphine (Ph₃ P). Typically, the reaction should take placeat a temperature of between about 130 and 180° C., preferably betweenabout 150 and 155° C. The reaction time is between about 3 and 5 hours,preferably about 3 hours.

Similarly, the reaction of the resin with an aromatic olefinic compoundaccording to the methods of the present invention is preferably carriedout in the presence of an acid catalyst. Suitable catalysts include, butare not limited to, H₂ SO₄, H₃ PO₄, aromatic and aliphatic sulfonicacids, and the like. The preferred catalyst is p-toluenesulfonic acid(PTSA). Typically, the reaction should take place at a temperature ofbetween about 130 and 180° C., preferably between about 150 and 155° C.The reaction time is between about 3 and 5 hours, preferably about 3hours.

One advantage of the method of the present invention is the productionof a non-volatile resin having a low free resorcinol content. Otheradvantages of the procedure are that it generates a low amount of wastesince yields are nearly 100%, has minimal toxicity levels, and usesrelatively low temperatures and low pressures.

In a preferred embodiment of the methods of the present invention,resorcinol is reacted with bisphenol A epoxy in the presence of a Ph₃ Pcatalyst. The reaction is performed at a temperature of between about150-155° C. for a period of between about 3-5 hours. The product of thisreaction and any unreacted or free resorcinol are then further reactedwith styrene in the presence of a PTSA catalyst. Again, the reaction isperformed at a temperature of between about 150-155° C. for a period ofbetween about 3-5 hours. The resulting product is a resorcinolic resinand a non-volatile adduct of resorcinol and styrene.

The methods of the present invention can also be used for producing lowfree resorcinol resins utilizing commercially available resins. Suchresins include commercially available resorcinol-formaldehyde resins,such as Penacolite® B-1A, Penacolite® B-18-S and Pentcolite® B-19-S,commercially available from Indspec Chemical Corporation, Pittsburgh,Pa. and commercially available resorcinol-modifiedalkylphenol-formaldehyde resins.

The present invention is further directed to a low free resorcinol resincomprising the addition product of an aromatic olefinic compound and aresin. Suitable resins include one or more resins selected from thegroup consisting of a dihydric phenol, a polyhydric phenol, a dihydricphenolic resin and a polyhydric phenolic resin; the addition product ofat least one of these resins and at least one compound selected from thegroup consisting of a monooxirane compound and a polyoxirane compound;and the phenol or alkyl or aralkyl substituted mono - or dihydric phenolmodified forms of these resins. Preferably, this low free resorcinolresin is prepared according to the method described above. The resinsalso have a low content of other free monomers. In a preferredembodiment, the resorcinolic resin addition product is that formedbetween resorcinol and bisphenol A epoxy, further reacted with styrene.

The resorcinolic resins, of the present invention are characterized asbeing non-volatile, that is, having free resorcinol content near zero.Accordingly, these resins can be used in any application in which anon-volatile, low free resorcinol resin is desired.

The resins of the present invention are particularly useful in rubbercompounding applications. Historically, resorcinol andresorcinol-formaldehyde resins have been used in the tire and rubberindustry as adhesion promoters for synthetic fabric and steel cord torubber bonding. Though resorcinol enhances both the mechanical andbonding properties of the cured rubber compounds, the volatility of thismaterial under rubber processing temperatures has prompted some tiremanufacturers to use precondensed resorcinol-formaldehyde novolak typeresins instead of a resorcinol monomer. The main advantage for usingthese resins in the rubber compound formulations is the reduction offree resorcinol content. The resins of the present invention serve toreduce the free resorcinol content even further. In addition, the resinsof the present invention can be produced at a low cost, and providecomparable performance for this application than those resins currentlycommercially available. In addition to their low free monomer content,the resins of the present invention, when used in rubber compoundingapplications, yield a low softening point that enhances the processingof the rubber, provides enhanced adhesion characteristics withreinforcements such as steel, polyester, nylon and others, and providesenhanced mechanical properties such as modulus and elongation.

The present invention is therefore further directed to a vulcanizablerubber composition having improvements in physical and mechanicalproperties such as dynamic stiffness, hardness, scorch safety and curetime. The vulcanizable rubber composition of the present inventioncomprises: (a) a rubber component selected from natural rubber,synthetic rubber or combinations thereof; (b) a methylene donor; and (c)a methylene acceptor. The methylene acceptor comprises the additionproduct of an aromatic olefinic compound and a resin; suitable resinsinclude one or more resins selected from the group consisting of adihydric phenol, a polyhydric phenol, a dihydric phenolic resin and apolyhydric phenolic resin; the addition product of at least one of theseresins and at least one compound selected from the group consisting of amonooxirane compound and a polyoxirane compound; and the phenol or alkylor aralkyl substituted mono - or dihydric phenol modified forms of theseresins. Thus, the methylene acceptor is the low free resorcinol resinsprepared by the methods described above.

Any suitable methylene donor can be used. Preferred arehexamethylenetetramine (HMTA), di-, tri-, tetra-, penta-, orhexa-N-methylol-melamine or their partially or completely etherified oresterified derivatives, for example hexamethoxymethylmelamine (HMMM),oxazolidine or N-methyl-1,3,5-dioxazine.

Typically, the methylene acceptor is incorporated into the rubbercomponent in an amount ranging from about 1 to 25 parts by weight basedon 100 parts by weight of the rubber component (1 to 25 phr).Preferably, the methylene acceptor is incorporated into the rubbercomponent in an amount from about 1 to 5 phr.

Generally, the weight ratio of methylene acceptor to methylene donor isfrom about 1:10 to 10:1, more preferably 1:3 to 3:1.

Typically, the mole ratio of the di- or polyhydric phenol or the di- orpolyhydric phenolic novolak resin to the mono- or polyoxirane compoundis between about 1:0.05 to 1: 1.5.

In a preferred embodiment, a vulcanizable rubber composition is providedas described above wherein the methylene acceptor is the additionproduct of resorcinol and the diglycidyl ether of bisphenol A, furtherreacted with styrene. The preferred embodiment also includes using Ph₃ Pas a catalyst when the addition product of resorcinol and diglycidylether of bisphenol A is formed and PTSA as a catalyst when furtherreacting this addition product with styrene.

It will be understood by those skilled in the art that it may bebeneficial to form the initial addition product of the methyleneacceptor in the presence of one or more solvents, including but notlimited to, aromatic hydrocarbons, such as toluene, xylene,ethylbenzene, or ketones such as methylisobutyl ketone.

It will be understood by those skilled in the art that the vulcanizablerubber composition of this invention may also include at least oneadditive comprising sulfur, carbon black, zinc oxide, silica, ananti-oxidant, a stearate, an accelerator, an oil or an adhesionpromoter. In the preferred embodiment, the methylene acceptor furtherincludes amorphous silica.

In another embodiment of this invention, a vulcanizable rubbercomposition is provided as described above, further comprising (d) areinforcing material. Any reinforcing material known in the art can beused, including, but not limited to, nylon, rayon, polyester, aramid,glass, steel (brass, zinc or bronze plated) or other organic andinorganic compositions. These reinforcing materials may be in the formof filaments, fibers, cords or fabrics.

Following formation of the rubber component, vulcanization can becarried out by methods known in the art.

It will be appreciated that the resin formed by the reaction of themethylene acceptor and methylene donor as described above promotesadhesion between the rubber and the reinforcing materials as describedabove while simultaneously providing an improvement in the rubbervulcanizate properties such as hardness and dynamic stiffness, as; wellas improving scorch safety time and providing longer cure times whencompared to the prior art. The rubber composition of the presentinvention further has improved adhesion properties for adhering rubberto the reinforcing materials as described above. Optionally, thereinforcing material can be pretreated or coated with adhesives.

EXAMPLES

The following examples are intended to illustrate the invention andshould not be construed as limiting the invention in any way.

EXAMPLE 1 Synthesis of Resorcinol-Bisphenol A Epoxy Resin

A 15 gallon reaction kettle equipped with a stirrer, temperaturecontroller, condenser and raw material addition setup was charged withapproximately 14.15 kg of resorcinol and 129 g of triphenylphosphineunder constant stirring. The reactor contents were heated to betweenabout 150 and 155° C. About 25 kg of diglycidyl ether of bisphenol A wasadded stream wise to the reactor over a period of about 1.5 hours. Thediglycidyl ether of bisphenol A was obtained from Dow Chemical asDER-331. Following addition of the epoxy, the reaction mixture wasstirred continuously at the same temperature for an additional period of1.5 hours. The resulting resin had a softening point of 84.3° C. and afree resorcinol content of 10.0 weight %. These results are shown inTable 1 below.

EXAMPLE 2 Synthesis of Styrene Modified Resorcinol-Bisphenol A EpoxyResin

The method of Example 1 was repeated in a 500 ml reaction kettle withabout 55 g of resorcinol, about 0.5 g of triphenylphosphine, and about98.6 g of the diglycidyl ether of bisphenol A. Following stirring of thereaction mixture for about 1.5 hours, about 0.7 g of para-toluenesulfonic acid (PTSA) was added to the reaction kettle and the mixturestirred for about 5 minutes. Then, about 13.0 g of styrene were addeddropwise from an addition funnel over a period of about 1.5 hours.Following completion of the styrene addition, the reaction mixture wasstirred for an additional period of about an hour. Following the hour,about 0.4 g of 50% aqueous sodium hydroxide solution was added toneutralize the acid catalyst. Finally, a vacuum of 28" Hg was applied toremove any unreacted monomers as distillate. The resulting resin had asoftening point of 89.0° C. and a free resorcinol content of 4.5 weight%. No distillate was collected during the vacuum dehydration, indicatingthe complete addition reaction between resorcinol and epoxy and furtherreaction with :styrene monomer. The results are shown in Table 1 below.

EXAMPLES 3-5 Synthesis of Styrene Modified Resorcinol-Bisphenol A EpoxyResins

The procedure of Example 2 was repeated in Examples 3 through 5 varyingthe amounts of styrene used. This amount, as well as the weight % offree resorcinol and the softening points of the resulting resins, areall shown in Table 1 below.

As can be seen from Table 1, no distillate was removed in any ofExamples 3 through 5, again demonstrating that resins with a low freeresorcinol content can be prepared according to the process of thisinvention. The results of these examples further indicate that a resinwith almost 100% yield is possible utilizing the methods of thisinvention.

                  TABLE 1    ______________________________________    Styrene Modified Resorcinol-Bisphenol A Epoxy Resin              Exam-  Exam-   Exam-   Exam- Exam-              ple 1  ple 2   ple 3   ple 4 ple 5    ______________________________________    Raw Materials    (grams)    1. Resorcinol                14.15 kg 55.0    55.0  55.0  110.1    2. Triphenylphosphine                 0.13 kg  0.5     0.5   0.5   1.0    3. DER-331   25.0 kg 98.6    98.1  97.4  195.2    4. PTSA     --        0.7     0.7   0.7   1.4    5. Styrene  --       13.0    26.0  52.0  156.0    6. Sodium Hydroxide                --        0.4     0.4   0.4   0.8    (50%)    Distillate Removed at                None     None    None  None  None    150-155° C./    28" Hg Vac.    Resin Properties    Softening Point (° C.)                84.3     89.0    89.4  90.7   92.2    Free Resorcinol                10.0      4.5     2.5   0.3   <0.01    (wt % by GC)    ______________________________________

EXAMPLES 6-7 Synthesis of Styrene Modified Commercially AvailableResorcinol Formaldehyde Resins

A 500 ml reaction kettle equipped with a stirrer, thermometer, reflexcondenser and addition funnel was charged with about 200 g ofPenacolite® B-1A, a commercially available resorcinol formaldehyde resinobtained from Indspec Chemical Corporation, under constant stirring. Theresin was heated to a temperature of between about 150 and 155° C. About1.0 g of PTSA was then added at the same temperature and mixed for about5 minutes. Styrene was then added dropwise over a period of about 3 to 4hours, in the amount indicated in Table 2. Following styrene addition,the reaction mixture was stirred for an additional period of about 1hour. Following the hour, about 0.5 g of 50% aqueous sodium hydroxidesolution was added to neutralize the acid catalyst. Finally, the resinwas dehydrated under vacuum (28" Hg) at 150 to 155° C. to remove anyunreacted styrene monomer in the form of a distillate. The results areshown in Table 2 below. As can be seen in Table 2, all of the styrenemonomer reacted with the resin material. Also, the unreacted resorcinolpresent in the Penacolite® B-1A resin was reduced due to its reactionwith styrene.

                  TABLE 2    ______________________________________    Styrene Modification on Resorcinol-Formaldehyde Resin                  Penacolite ® Resin B-1A    Resin Used      Control  Example 6  Example 7    ______________________________________    Raw Materials (grams)    1. Resin        200.0    200.0      200.0    2. PTSA         --        1.0        1.0    3. Styrene      --        20.0       80.0    4. Sodium Hydroxide (50%)                    --        0.5        0.5    Distillate Removed at    150-155° C./28" Hg Vac.                    --        0.1        0.2    Resin Properties    Softening Point (° C.)                     94.2    101.0      107.2    Free Resorcinol  17.5     12.0       5.0    (wt % by LC/GC)    ______________________________________

EXAMPLES 8-9 Synthesis of Styrene Modified Resocinol-Formaldehyde Resins

The procedure of Examples 6 and 7 was repeated using RM-441 modifiedresorcinol-formaldehyde resins commercially obtained from IndspecChemical Corporation as Penacolite® B-18-S and Penacolite® B-19-S.RM-441 is a water soluble resorcinol oligomer obtained from themanufacture of resorcinol, and has a typical composition of about 2 to 8weight % resorcinol, 2 to 12 weight % dihydroxydiphenol, 25 to 35 weight% trihydroxydiphenol and the balance higher molecular weight polymers.Penacolite® B-18-S and B-19-S resins contain about 18 weight % and 11weight % free resorcinol, respectively. The amount of each startingmaterial used, as well as properties of the resulting products, areshown in Table 3. As can be seen from the table, a negligible amount ofdistillate was obtained, therefore indicating that all of the styrenereacted with the Penacolite® resins. In addition, the free resorcinolcontent of the final modified resins was lower when using the styreneaddition, as compared to the control values.

                  TABLE 3    ______________________________________    Styrene Modification of    RM-441 Modified Resorcinol-Formaldehyde Resins               Penacolite ® B-18-S                           Penacolite ® B-19-S    Resin Used   Control  Example 8                                   Control                                          Example 9    ______________________________________    Raw Materials (grams)    1. Resin     200.0    200.0    200.0  200.0    2. PTSA      --        1.0     --      2.0    3. Styrene   --        80.0    --      80.0    4. Sodium Hydroxide                 --        0.5     --      1.0    (50%)    Distillate Removed at    150-155° C./                 --        0.1     --      0.3    28" Hg Vac. (grams)    Resin Properties    Softening Point (° C.)                 101.1    105.0    102.7  108.4    Free Resorcinol                  17.5     4.5      10.5   5.0    (wt. % LC/GC)    ______________________________________

EXAMPLE 10 Styrene Modification on Resorcinol Modified Phenolic Resin

The methods of Examples 6-9 were repeated using a resorcinol modifiedalkylphenol-formaldehyde resin. This resin contained about 10.0 weight %of free resorcinol and had a softening point of about 100° C. The amountof each starting material used, as well as the results, are presented inTable 4 below. As can be seen from Table 4, a higher distillate amountwas removed in this example. The distillate amount can be lowered byincreasing the amount of catalyst and the reaction time. In addition,the free resorcinol content was less than 1.0 weight %.

                  TABLE 4    ______________________________________    Styrene Modification of    Resorcinol Modified Alkylphenol-formaldehyde Resin                      Control                            Example 10    ______________________________________    Raw Materials (grams)    1. Resin            200.0   200.0    2. PTSA             --       1.0    3. Styrene          --       80.0    4. Sodium Hydroxide (50%)                        --       0.5    Distillate Removed at                        --       4.5    150-155° C./28" Hg Vac. (grams)    Resin Properties    Softening Point (° C.)                        100     116.2    m/p cresols          7.0     5.5    Free Resorcinol (wt %, LC/GC)                         10.0     0.25    ______________________________________

EXAMPLE 11 Synthesis of Styrene Modified Resorcinol-Bisphenol A EpoxyResin

A 4 liter reaction kettle equipped with a stirrer, thermometer, reflexcondenser and addition funnel was charged with about 440.4 g ofresorcinol and about 4.0 g of triphenylphosphine under constantstirring. The mixture was heated to a temperature of between about150-155° C. About 778 g of the diglycidyl ether of bisphenol A wereslowly added to the mixture over a period of about 1.5 hours. About 12 gof PTSA were then added to the kettle and mixture stirred for about 5minutes at the same temperature. Then, about 305.5 g of styrene wereadded dropwise from the addition funnel over a period of about 1.5 hoursat the same temperature. Following styrene addition, the reactionmixture was stirred for an additional period of about 1 hour, afterwhich time about 6.0 g of 50% aqueous sodium hydroxide solution wereadded to neutralize the PTSA catalyst. Finally, vacuum was applied (28"Hg) at the same temperature to remove the water condensate whichresulted from the catalyst and sodium hydroxide solution. The resultingresin (identified herein as 125-302) had a softening point of 91.6° C.and a free resorcinol content of about 1.0 weight %.

EXAMPLE 12 Evaluation of Styrene Modified Resorcinol-Bisphenol A EpoxyResin

The resin prepared according to Example 11 was evaluated in a blacknatural rubber compound to assess and compare its performance againstcommercially available resorcinol-based resins, Penacoliteg B-20-S,commercially available from Indspec Chemical Corporation, and ALNOVOLVPN 1755, available from Hoechst Chemical. Penacolite® B-20-S typicallyhas a softening point of about 104° C. and a free resorcinol content of3%; ALNOVOL VPN 1755 has a softening point of about 1 15° C. with a freeresorcinol content of about 1%. Black natural rubber compositions havingthe formulation shown in Table 5 were prepared in a 3-stage mixingprocedure. These rubber compositions were then used to evaluate theadhesion and reinforcing effects of the resorcinol compounds of thisinvention as methylene acceptors in combination with the methylene donorhexamethoxymethylmelamine (HMMM). The resins were tested at theirestimated optimal weight ratios at constant combined loadings of 4 partsby weight in the rubber compound.

                  TABLE 5    ______________________________________    Rubber Compound for Adhesion and Mechanical Properties    Masterbatch                 phr.sup.(1)    ______________________________________    Natural Rubber              100.0    Carbon Black N-326          55.0    Zinc Oxide                  8.0    Stearic Acid                1.0    N-(1,3-Dimethyl butyl)-N'-Phenyl-p-Phenylene Diamine                                2.0    Polymerized 1,2-Dihydro-2,2,4-Trimethylquinoline                                1.0    N-(Cyclohexylthio)Phthalimide                                0.2    Total                       167.2    Insoluble Sulfur             4.00    N,N-Dicyclohexyl-2-Benzothiazolesulfenamide (accelerator)                                 1.00    Cobalt Boron Complex (22.5%)                                 0.45    Methylene Acceptor/Donor Ratio                                2.4/1.6    ______________________________________     .sup.(1) parts by weight per 100 parts of rubber

The rubber master batch was mixed in the first stage to about 150° C. ina Banbury mixer. In a second stage, a methylene acceptor preparedaccording to the methods of Example 11 designated herein as 125-302,with the inclusion of a cobalt boron complex was then mixed into anappropriate amount of the master batch on the 2-roll mill at about 121 °C. The insoluble sulfur, accelerator and appropriate amount of HMMM asindicated in Tables 5 and 6 were mixed in the third stage at 95° C. Thetest compounds were conditioned overnight in a constant temperature roomat about 23° C. and 50% relative humidity. The compounds were thentested for rheometer cure, shaped and optimum cured at 150° C. for theevaluation of wire adhesion and mechanical properties.

Cure properties were measured with a Monsanto 100 rheometer at 150° C.,1° arc and 1.67 Hz according to ASTM D 2084. Wire pullout adhesion wasdetermined for each test compound by ASTM D 2229 using 3 ×0.2+6×0.35brass-plated steel cord with 63.5% copper plating embedded in 19.0 mm inthe rubber pad. Dynamic mechanical properties were determined with aRheometrics Scientific mechanical spectrometer at 0.2 and 2.0% torsionalsheer strain at 1 Hz and 23° C. Dynamic stiffness G' was measured at0.2% strain and tangent delta, an indicator of compound hysteresis orheat buildup, was measured at 2.0% strain.

The commercial methylene acceptors, Penacolite® B-20-S and VPN 1755, andresin 125-302 were each combined with methylene donor HMMM and evaluatedfor cure, wire adhesion and mechanical properties, as discussed above.The test data are given in Table 6. As can be seen from the table,Compound C made with the 125-302, methylene acceptor of the presentinvention was observed to be non-fuming and was comparable to thecontrol resins, Compounds A and B. The rheometer cure properties, torquerise MH-ML, scorch time t_(s2) and optimum cure time t'₉₀ of Compound Cwere also comparable to control Compounds A and B. The initial, steamand humidity aged wire adhesion of Compound C was also comparable tocontrol Compounds A and B. In addition, Compound C developed similartensile properties and hysteresis (tangent delta) with higher dynamicstiffness (G') and hardness than the controls.

                  TABLE 6    ______________________________________    Rubber Compound Properties                 Compound                 A       B         C    ______________________________________    Methylene Acceptor/                   B-20-S/   VPN-1755/ 125-302/    Donor          HMMM      HMMM      HMMM    Weight Ratio acceptor/donor,                   2.4/1.6   2.4/1.6   2.4/1.6    phr    Fuming at 120° C.                   Slight    None      None    Rheometer Cure at 150° C.    MH-ML, dN-m    43.2      40.7      42.6    t.sub.s2, minutes                   4.6       5.4       5.3    t'.sub.90 minutes                   19.2      20.5      22.8    Wire Adhesion N    (% Rubber Coverage)    Unaged         1246 (88) 1146 (83) 1114 (85)    Steam, 16 hours at 120° C.                   1271 (90)  1266 (100)                                       1282 (90)    Humidity, 14 days at    85° C./95% R.H.                   1243 (95) 1172 (90) 1182 (90)    Dynamic Mechanical    G' at 0.2% strain MPA                   23.10     19.40     26.60    Tangent Delta at 2.0% Strain                    0.198     0.209     0.206    Shore A Hardness                   81        77        93    Tensile Properties    100% Modulus, MPa                    4.56      4.55      4.75    Tensile Strength, MPa                   28.18     28.23     28.06    Elongation, %  458       455       458    ______________________________________

In short, the resin produced by the methods of the present inventiongave improved compound mechanical properties while maintaining therheometer cure and brass wire adhesion properties of the commerciallyavailable control resins. Thus, the present invention provides resinswith low free resorcinol content that do not sacrifice performance whencompared with resins known in the art.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

What is claimed is:
 1. A method for reducing the free phenolic monomercontent in a compound comprising reacting an effective amount of anaromatic olefinic compound with the free phenolic monomer in saidcompound; wherein the compound is selected from the group consistingof:(a) one or more resins selected from the group consisting of amonohydric phenolic resin, a clihydric phenolic resin and a polyhydricphenolic resin; (b) the addition product of at least one compoundselected from the group consisting of a dihydric phenol, a polyhydricphenol, a dihydric phenolic resin and a polyhydric phenolic resin, andat least one compound selected from the group consisting of amonooxirane compound and a polvoxirane compound; and (c) a monohydricphenolic resin, a dihydric phenolic resin or a polyhydric phenolic resinthat comprises one or more substituents selected from the groupconsisting of an alkyl group and an aralkyl group; and wherein saidaromatic olefinic compound is selected from the group consisting ofvinyl naphthalene and aromatic olefinic compounds having the formula##STR4## wherein (R) is selected from the group consisting of H, CH₃ andhalogen; and R₁ is independently selected from the group consisting ofH, OH, an alkyl group having from 1 to 6 carbons, a halogen and--CH=CH₂.
 2. The method of claim 1, including preparing said additionproduct of at least one compound selected from the group consisting of adihydric phenol, a polyhydric phenol, a dihydric phenolic resin and apolyhydric phenolic resin and at least one compound selected from thegroup consisting of a monooxirane compound, and a polycixirane compoundby reacting at least one member selected from each group in the presenceof a catalyst selected from the group consisting of trialkylphosphine,triarylphosphine, trialkylamine, dialkylaminomethylated phenol,4-dimethylaminopyridine and a quaternary ammonium compound.
 3. Themethod of claim 2, including employing triphenylphosphine as saidcatalyst.
 4. The method of claim 2, including performing said reactionat a temperature between about 130 and 180° C. for between about 3 and 5hours.
 5. The method of claim 1, including employing a di- or polyhydricphenolic resin selected from the group consisting of resorcinol,catechol, dihydroxybiphenol, trihydroxybipheriol, hydroquinone,alkylidenebisphenols wherein said alkylidene group has from about 1 to12 carbon atoms, and thiobisphenols; and wherein said di- or polyhydricphenolic resin is optionally substituted by at least one of the groupscomprising an alkyl group having from about 1 to 12 carbon atoms, anaralkyl group having from about 6 to 12 carbon atoms, an alkanoyl grouphaving from about 2 to 18 carbon atoms, an aroyl group having from about7 to 11 carbon atoms, or a halogen selected from the group consisting ofchlorine and bromine.
 6. The method of claim 1, including employing amonooxirane compound selected from the group consisting of a saturatedor unsaturated alkylene oxide having from about 2 to 18 carbon atoms, aglycidyl ether compound, a glycidyl ester compound, and mixturesthereof; and including employing a polyoxirane compound selected fromthe group consisting of a 4-vinylcyclohexene dioxide, epoxidizedglycerides of unsaturated fatty acids, epoxidized nitrogen-containingmaterial, polyglycidyl ethers, polyglycidyl esters, and mixturesthereof.
 7. The method of claim 1, including employing resorcinol assaid dihydric phenolic resin and a diglycidyl ether of bisphenol A assaid polyoxirane compound.
 8. The method of claim 2, further includingthe step of adding amorphous silica during said reaction.
 9. The methodof claim 3, including employing a molar ratio of said di- or polyhydricphenol or said di- or polyhydric phenolic resin to said monooxiranecompound, or polyoxirame compound in said addition product of betweenabout 1:0.05 to 1:1.5.
 10. The method of claim 1, including performingthe reaction between said resin and said aromaitic olefinic compound inthe presence of a catalyst selected from the group consisting of H₂ SO₄,H₃ PO₄, aromatic sulfonic acids and aliphatic sulfonic acids.
 11. Themethod of claim 10, including employing p-toluene sulfonic acid as saidcatalyst.
 12. The method of claim 10, including performing said reactionat a temperature between about 130 and 180° C. for a period of betweenabout 3 to 5 hours.
 13. The method of claim 1, including employing anaromatic olefinic compound selected from the group consisting ofalpha-methylstyrene, p-methylstyrene, alpha-chlorostyrene,divinylbenzene and vinyl naphthalenes.
 14. The method of claim 13,including employing styrene as said aromatic olefinic compound.
 15. Acompound having less than 10% volatile free phenolic monomer, saidcompound comprising the additional product of said free phenolic monomerand an aromatic olefinic compound, wherein said compound is selectedfrom the group consisting of:(a) one or more resins selected from thegroup consisting of a monohydric phenolic resin, a dihydric phenolicresin and a polyhydric phenolic resin; (b) the addition product of atleast one compound selected from the group consisting of a dihyclricphenol, a polyhydric phenol, a dihydric phenolic resin and a polyhydricphenolic resin, and at least one compound selected from the groupconsisting of a monooxirane compound and a polyoxirane compound; and (c)a monohydric phenolic resin, a dihydric phenolic resin or a polyhydricphenolic resin that comprises one or more substitutients selected fromthe group consisting of an alkyl group and an aralkyl group; and whereinsaid aromatic olefinic compound is selected from the group consisting ofvinyl naphthalene and an aromatic olefinic compound having the formula(3) ##STR5## wherein (R) is selected from the group consisting of H, CH₃and halogen; and R₁ is independently selected from the group consistingof H, OH, an alkyl group having from 1 to 6 carbons, a halogen and--CH=CCH₂.
 16. The compound of claim 15, wherein said di- or polyhdricphenolic resin compound is selected from the group consisting ofresorcinol, catechol, dihydroxybiphenol, trihydroxybiphenol,hydroquinone, alkylidene bisphenols, wherein said alkylidene group hasfrom about 1 to 12 carbon atoms, and thiobisphenols; and wherein saiddi- or polyhydric phenolic resin is optionally substituted by at leastone of the groups comprising an alkyl group having from about 1 to 12carbon atoms, an aralkyl group having from about 6 to 12 carbon atoms,an alkanoyl group having from about 2 to 18 carbon atoms, an aroyl grouphaving from about 7 to 1 1 carbon atoms, or a halogen selected from thegroup consisting of chlorine and bromine.
 17. The compound of claim 15,wherein said monooxirane compound is selected from the group consistingof saturated or unsaturated alkylene oxides having from about 2 to 18carbon atoms, a glycidyl ether compound, a glycidyl ester compound, andmixtures thereof; and wherein said polyoxirane compound is selected fromthe group consisting of a 4-vinylcyclohexene dioxide, epoxidizedglycerides of unsaturated fatty acids, epoxidized nitrogen-containingmaterial, polyglycidyl ethers, polyglycidyl esters, and mixturesthereof.
 18. The compound of claim 15, wherein said dihydric phenolicresin is resorcinol and said polyoxirane compound is a diglycidyl etherof bisphenol A.
 19. The compound of claim 15, further including anamorphous silica.
 20. The compound of claim 15, wherein the molar ratioof said di- or polyhydric phenol or said di- or polyhydric phenolicresin to said monooxirane compound, alkylene carbonate or polyoxiranecompound in said addition product is between about 1:0.05 to 1:1.5. 21.The compound of claim 15, wherein said aromatic olefinic compound isselected from the group consisting of alpha-methylstyrene,p-methylstyrene, alpha-chlorostyrene, divinylbenzene and vinylnapthalenes.
 22. The compound of claim 15, wherein said aromaticolefinic compound is styrene.
 23. The compound of claim 15, furthercharacterized as being useful in rubber compounding applications.